Various regions throughout the world are subject to sharply defined seasons wherein the rain or snowfall during certain wet months far exceeds the precipitation which falls during dry periods. The resulting water shortages which occur during the dry months are particularly acutely felt in places such as Florida and California where agriculture is a year round industry and where a constant source of water for irrigation is required. During recent years, excessively hot, dry summers have devastated many farming regions both in the United States and around the world. This problem is particularly frustrating because much of the excess rain which falls during the wet periods evaporates or otherwise dissipates and is never used. A need has therefore arisen for a water management system which permits the storage of excess water that accumulates during the wet or rainy season for subsequent use in agricultural irrigation during the ensuing dry season.